Fix float16 support [#2379] (#2483)

* Fix float16 support [#2379]

Convert to float32 on startup unless backed, in which case error. scipy does not support complex slicing from float16 data so this is the easiest fix for now.

* minor msg change

test/unit/data_anndata/test_anndata_adaptor.py

@@ -1,5 +1,4 @@
 import json
-import sys
 import time
 import unittest
 
@@ -37,6 +36,7 @@ Test the anndata adaptor using the pbmc3k data set.
         (f"{FIXTURES_ROOT}/pbmc3k-CSC-gz.h5ad", True, "normal"),
         (f"{FIXTURES_ROOT}/pbmc3k-CSR-gz.h5ad", True, "normal"),
         (f"{FIXTURES_ROOT}/pbmc3k_64.h5ad", False, "auto"),  # 64 bit conversion tests
+        (f"{FIXTURES_ROOT}/pbmc3k_16.h5ad", False, "auto"),  # 16 bit conversion tests
     ],
 )
 class AdaptorTest(unittest.TestCase):

test/unit/data_anndata/test_anndata_adaptor_errors.py

@@ -0,0 +1,23 @@
+import unittest
+
+from parameterized import parameterized_class
+
+from server.common.errors import DatasetAccessError
+from test import FIXTURES_ROOT
+from test.unit import app_config
+
+
+@parameterized_class(
+    ("data_locator", "backed", "X_approximate_distribution"),
+    [
+        (f"{FIXTURES_ROOT}/pbmc3k_16.h5ad", True, "auto"),  # 16 bit conversion tests
+    ],
+)
+class AdaptorLoadErrorTest(unittest.TestCase):
+    def test_float16_backed_raises_err(self):
+        with self.assertRaises(DatasetAccessError):
+            config = app_config(
+                self.data_locator,
+                backed=self.backed,
+                extra_dataset_config=dict(X_approximate_distribution=self.X_approximate_distribution),
+            )